SYMPTOM
Prolonged labour
Prolonged labour may show as a bitch or queen straining hard without a puppy or kitten appearing, a long gap after one or more births while more young are expected, or restlessness, nesting and panting that go on without straining beginning, for many hours in a bitch or well beyond two hours in a queen. Some owners notice a dark green or black discharge (brown in queens) with no birth following, a puppy or kitten visible at the vulva that does not move on, a stillborn puppy or kitten, or a mother who is trembling, weak or unusually flat. In dogs, puppies typically arrive 15 to 60 minutes apart, and dystocia is suspected when strong straining continues for around 30 minutes without a birth, more than one to two hours pass between puppies, visible contractions go on for more than four hours without the first puppy, or no delivery follows within 12 to 24 hours of first-stage signs beginning. In queens, the first kitten usually arrives within about an hour of visible contractions beginning, although strong, sustained straining for more than 30 minutes without a kitten is itself outside the usual pattern. Later kittens usually follow 10 to 60 minutes apart, with a median gap of about 30 minutes, and in one UK study of pedigree litters about 86 in 100 queens delivered the whole litter within six hours of the first kitten. In a queen, the published markers are more than 30 minutes of strong straining without a kitten, more than two hours between kittens while more are expected, or more than four hours of visible contractions without a first kitten. A queen resting and nursing between kittens can look much the same as one whose labour has stalled, so these intervals carry more information than how settled she seems.
Mechanical obstruction
Prolonged labour can reflect a physical mismatch between the birth canal and the size or position of a puppy or kitten. This may involve an unusually large offspring, an abnormal presentation such as breech or transverse position, or pelvic narrowing from previous injury or developmental variation.
Uterine inertia
Uterine inertia, where the uterine muscles fail to contract with sufficient strength or frequency to progress labour, is the most frequently identified cause of prolonged labour in both bitches and queens. It can be present from the start (primary) or develop when the uterus tires after straining against an obstruction (secondary). It is more likely when litter size is very large or very small, or when metabolic disturbances such as low calcium or glucose alter muscle function.
Maternal systemic factors
Conditions affecting the mother's overall health can interfere with the normal progression of labour. These may include hormonal imbalances, infections of the reproductive tract, metabolic derangements, or cardiovascular compromise that limits the body's ability to sustain the physical demands of parturition.
Foetal abnormality or distress
Developmental anomalies in the offspring, foetal death prior to delivery, or distress during labour can alter the normal signals that coordinate uterine contractions and cervical dilation. These changes may slow or halt the progression of birth.
Breed and anatomical predisposition
Certain breeds with particular skull shapes, body proportions, or pelvic configurations tend to experience more difficulty during parturition. Breeds whose puppies have broad heads relative to the dam's pelvis face higher rates of obstructed labour, as do animals with narrow pelvic canals. In Bulldogs, French Bulldogs and Boston Terriers, more than 80 in 100 litters are born by caesarean section.
Normal variation in labour
Not every long labour is abnormal. First-stage labour, with restlessness, nesting and panting, can last many hours in a bitch, with delivery typically following within 12 to 24 hours, while in most queens this stage lasts under two hours. Puppies commonly arrive 15 to 60 minutes apart with rests in between, and a queen may rest and nurse calmly between kittens, though most queens have delivered the whole litter within about six hours of the first kitten and more than two hours between kittens sits outside the usual pattern. Unproductive straining, discharge before the first birth, and weakness or distress in the mother all point away from a normal rest, but their absence does not show that labour is progressing; the time since the last birth carries more information than how settled the mother seems.
Why timing matters
Early observation
When labour appears prolonged in its early stages, the pattern often reflects either a delay in the onset of productive contractions or difficulty with the first offspring in the birth canal. Some animals experience a period of restlessness and intermittent straining before active labour begins, and distinguishing preparatory activity from true obstruction can be challenging. The duration of straining without producing offspring, the intensity of contractions, and the presence of discharge can all offer clues, but whether a puppy or kitten is lodged, lies abnormally or is still alive cannot be determined by watching; that is established by examination, radiographs or ultrasound.
Later presentation
If prolonged intervals develop between the delivery of individual offspring, the picture may shift towards uterine fatigue, particularly in larger litters. The uterus may begin to contract less effectively as time passes, or a mechanical problem may emerge partway through the process. A mother who has stopped straining can look calmer while the situation is worsening, because a uterus that has tired against an obstruction contracts less (secondary inertia). Changes in discharge and behaviour add information, but they do not show whether the remaining young are alive or whether one is blocking the birth canal.
Labour in dogs and cats tends to follow a pattern of cervical dilation, active straining, and delivery of offspring at intervals, but individual variation is considerable. Some animals deliver an entire litter within a few hours, while others rest for longer between births, though a gap of more than two hours falls outside the usual pattern in either species. The total duration that may be considered within normal range varies by species, breed, and individual history. Prolonged labour changes over hours rather than days. Once a placenta separates, the young attached to it is losing its oxygen supply, and the longer labour goes on, the more likely stillbirths become. For the mother, prolonged or obstructed labour can lead to exhaustion, low blood calcium, uterine rupture where contractions are driven against a blockage, and infection from dead foetuses left in the uterus. Medication to strengthen contractions is used only once an obstruction has been excluded, because driving contractions against a blockage risks rupture.
Conditions commonly associated
Dystocia
Prolonged labour is a form of dystocia, which complicates around 5 in 100 pregnancies in bitches and 3 to 6 in 100 in queens. It changes over hours, as separating placentas cut the oxygen supply to the young still inside and a tiring uterus contracts less.
Eclampsia in Dogs
Eclampsia typically develops in the weeks after birth, but in some cases falling calcium levels can begin during late pregnancy or active labour, and this metabolic disturbance can weaken uterine contractions, contributing to prolonged labour.
Hypothyroidism in Dogs
Hypothyroidism can reduce metabolic rate and affect muscle function throughout the body, and in pregnant dogs this may include weakened or inefficient uterine contractions during labour. In an experimental study of bitches with short-term induced hypothyroidism, contractions were weaker, parturition was prolonged and puppy deaths around birth were more frequent, and a later study found that treating the thyroid deficiency reversed the raised puppy mortality and low birth weight.
Uterine Inertia
When the uterus fails to contract effectively, labour continues well beyond the expected time without progressing to delivery.
Brachycephalic Obstructive Airway Syndrome (BOAS) in Dogs
Bulldogs, French Bulldogs and Boston Terriers have high rates of caesarean delivery, partly because the puppies' broad heads pass poorly through the dam's pelvis. The same breeds' airway anatomy adds to the risks of anaesthesia and recovery if surgery is needed.
Obesity in Dogs
Obesity in the bitch is listed among the factors that predispose to uterine inertia, though how it does so is not established. It also adds to anaesthetic risk if a caesarean section is needed.
When to explore further
If strong straining continues for around 30 minutes without producing an offspring, if more than one to two hours pass between puppies, or more than two hours between kittens, while more are expected, if visible contractions have gone on for more than four hours without the first puppy or kitten, or if a puppy or kitten is visible at the vulva and does not progress. Whether young remain, and whether they are alive, cannot be judged from outside.
If the mother shows signs of weakness, collapse, pale gums, or trembling, at any stage of labour. Trembling and stiffness can reflect low blood calcium, and weakness can reflect exhaustion or blood loss.
If a dark green or black discharge (brown in queens) appears before the first puppy or kitten and no birth follows within about 15 to 30 minutes, since this can mean a placenta is separating while the young attached to it is still inside, or if fresh blood appears in significant volume.
If the mother appears distressed, vocalises persistently, or becomes unresponsive to her surroundings during labour.
If there is a known history of previous caesarean section, pelvic injury, or difficulty in prior pregnancies.
If restlessness, nesting and panting have continued for 12 to 24 hours in a bitch, or well beyond the two hours within which most queens begin straining, without a birth, if the rectal temperature fell (in dogs, typically below about 37.2°C) more than 24 hours earlier without labour starting, or if pregnancy has run beyond its expected length.
If a stillborn puppy or kitten is delivered, since the young still inside may be compromised in the same way.
The details that help a veterinary team are simple ones: when nesting and panting began, when strong straining started, the time each puppy or kitten was born, the colour and timing of any discharge, whether any young were stillborn, the expected litter size where a scan or radiograph gave one, the mating dates, and any previous difficult birth or caesarean. These notes speed the choice between medical support and surgery, but they do not replace examination. Whether young remain, how they lie and whether they are alive are established by palpation, radiographs and ultrasound, and labour that has already passed the timings described on this page is changing hour by hour.
Last reviewed: 9 October 2026 · Dr Alastair Greenway MRCVS